Method and apparatus for registering a time-dependent quantity to be measured

ABSTRACT

Dosimetric data are registered in several channels as a directly readable bar chart, the height of the readable registration of each respective bar being a direct measure of the integrated dose value of the associated channel. Preferably, the registration is made by means of a measurement signal transducer (1) and a measurement interval separator (3) connected thereto, the separator controlling a number of parallel registration channels, each of the channels including a LED (10-13), a film (28) for integrating registration of radiation emitted by the LED, a slot-shaped aperture opening (34-37) for providing a bar-shaped incidence of radiation flow on the film, and a wedgy grey filter (30-33) attanuating the radiation intensity of the flow striking the film stepwise or continuously in the direction of the bar.

TECHNICAL FIELD

The present invention relates to the registration or recording of ameasured quantity, which is time-dependent, and which is present in theform of an electrical signal, the registration being of the kindincluding conversion or transformation of the signal to an emission orradiation flow, with detection and integrating registration of thusgenerated emission by means of an element sensitive to said emission,said element thus being given a subsequently readable, integratedmeasurement value registration correpsonding to a time function of thequantity to be measured. The obtained measurement value registration canespecially represent an exposure dose.

BACKGROUND ART

Registration of the kind mentioned above is already known, e.g. from theSwedish patent No. 7413396-8. This publication describes a so-calledaudio or noise dosimeter, which includes a microphone transmitting anelectrical signal in response to sound picked up by it, said signalbeing supplied to two parallel light-emitting diode (L.E.D.) circuitsafter filtering and amplification. Each circuit has a LED, which isenergised for emitting light when the input signal to the circuit iswithin a given interval corresponding to a given sound level interval.Each LED has allotted to it a given portion of a photographic film,where the emission flow of the associated LED is detected andintegratingly recorded as a film darkening. After a recording process,which may include an arbitrary time period, either continuous orcomprising partial periods, the film will accordingly carry a number ofintegrated measurement value registrations (dose records) correspondingto the number of measurement intervals, i.e. to the number of LEDs, eachregistration representing the noise dose for the associated measurementinterval. The respective noise doses may be subsequently established bydetermining the degree of darkening (after developing the film) on therespective portions of the film by comparison with known degrees ofdarkening, e.g. in a so-called densiometer.

A recording apparatus that is constructed in accordance with the knownprinciples described above affords a number of advantages, such as:Permitting registration of measured quantity sequences having very shortduration, e.g. sound impulses; Operation entirely without moving parts;Easily miniaturizable utilizing modern transducer and other circuit andelectronics components, making it particularly well suited toapplications for personal wear.

This known kind of registering apparatus has a clear disadvantagehowever, since the actual determination of an obtained measurement valueis complicated, and requires densiometric equipment or other similar,advanced laboratory equipment.

OBJECT OF THE INVENITON

The object of the present invention is thus to provide a new, improvedmethod of registration, of the kind mentioned in the introduction, bymeans of which said disadvantage is overcome, in that a direct readingof the obtained measurement value is enabled, other advantages alsobeing gained such as excellent possibilties of adaptation to differentregistration requirements, and the possibility of accuratemulti-interval registration, even in cases where greatly differingactivities of quantities to be measured can be expected in the variousmeasurement intervals.

SUMMARY OF THE INVENTION

The above-mentioned object is achieved in accordance with the inventionby a method and apparatus being given the features set forth in theappended claims.

The invention thus means that the element detecting and integratinglyrecording the generated emission or radiation for every desiredmeasurement value relatable to the measured quantity as such, or a giveninterval for the measured quantity value, is provided with aregistration, the readable extension of which constitutes a directlydeterminable measure of the desired measurement value. In other words,the extent of the readable registration on the element increasesaccording as the received integrated emission flow increases. Theextension of the registration may be continuous or stepwise, withcohesive or separate zone parts or portions. Preferably, registration ismade in the form of a bar, the readable extent of which (growing duringa registration sequence) will be a direct measure of the recordedmeasurement value. The extension characteristic of the registration maybe adapted to expected, measured quantity sequence, registrationduration time, etc., and in principle it may be linear or logarithmic,for example.

According to one aspect of the invention, there is thus provided aregistration method of the kind mentioned, distinguished in that thegenerated emission flow, preferably in response to the measured quantityvalue and particularly for a preselected measured quantity interval, iscaused to affect a plurality of preferably continuous parts or portionsof said element so that each portion is given a readable, partialregistration when the appropriate portion has been subjected to anemission effect corresponding to a unique, integrated partialmeasurement value allotted to the portion, wherein, after a registrationsequence, each part or portion having a readable partial registrationindicates that at least an integrated measurement value corresponding tothis part or portion has been recorded, the greatest readably, partialmeasurement value then representing a directly readable, integratedmeasurement value. It will be understood that in conjunction withprinciply continuously growing registration, the individual parts orportions will have very small or infinitesemal extension.

To advantage, the generated emission flow is caused to affect saidelement spread out, preferably in the form of a bar including said partsor portions, there being provided at emission influence a registrationeffect per unit of time, preferably a film darkening effect, which has apredetermined unique magnitude for each respective one of the variousparts or portions of the emission-influenced zone of said element. It issuitable here to make the emission intensities incident on the variousparts or portions of the emission affected or influenced zone of saidelement continuously or stepwise reduced in relation to each otherand/or to use an element having different sensitivities to the emissionwhich are continuously or stepwise reduced in relation to each other forthe various portions of the zone affected by the emission. Preferably,by selective filtering of the emission flow, the flow is caused tostrike with different intensities respective portions of the zoneaffected by emission on said element. It is also possible, however, togenerate the emission flow such that it includes, per se, portions withdifferent, suitable emission intensitites.

The method in accordance with the invention may also include giving thevarious portions of the emission-affected zone of said element differentpre-registrations such as pre-irradiations, so that in conjunction witha registration process, each portion is given a readable partialregistration for a particular emission effect, unique to that portion.It will be understood that pre-registration may be combined with one ormore of the previously described measures.

According to another aspect of the invention, there is provided anapparatus for registering a time-dependent quantity to be measured,which is in the form of an electric signal, the apparatus comprisingmeans for converting or transforming the electric signal to an emissionor radiation flow, which is specifically allotted a measurement valueregistration, and preferably including means for controlling theconversion in response to the measured quantity value, particularly sothat the conversion and therewith associated registration take placewhen said value is within a predetermined interval; an element havingthe ability of detecting and integratingly registering the emission inquestion, such as a photographic film; and emission control means forcausing the emission flow generated by said conversion means to strikesaid detection and registration element for affecting it, so that theelement is given an integrated measurement value registrationcorresponding to a time function of the measured quantity, such as anexposure dose, the apparatus being distinguished in that said conversionand emission control means are arranged to provide the incidence of saidemission flow on a zone or area of said element, comprising a number ofparts or portions preferably in the form of a bar, continuously merginginto each other or stepwise cohesive, and in that means are arranged forcausing the emission flow to strike with different intensities therespective portions of the emission-affected zone of said element and/orin that the portions of said zone of the element are arranged to have aunique limit value for the respective portion for the integratedemission effect required to give a readable partial registration on therespective portion. Said means providing different incident emissionintensities include to advantage filter-means adapted for selectivelymoderating the portions of the generated emission flow incident on therespective portions of the emission-affected zone. Said filter means arehere given an emission alternating characteristic adjusted to theemission intensity incident on the filter, the emission sensitivity ofsaid element and expected recorded dose (i.e. expected total action timeof the measured quantity) during a recording process, which maynaturally embrace a period of time having greatly varying duration, e.g.from minutes to days, weeks or longer, according as the field of use.

For the purpose of providing the above-mentioned unique limit values,the various portions of the emission-affected zone suitably havedifferent emission sensitivities. In the use of an element in the formof a photographic film, this has a suitably graded sensitivity in thevarious portions of the emission-affected zone. It is also possible tohave an element, the various portions of which have been given differentpreregistrations, the portion first to have a readable registration (lowmeasurement value) when emission-affected suitably having been givenheavy preregistration and vice versa, i.e. the portion to have areadable registration for a large measurement value having been givenslight, or no preregistration.

It will be understood that the invention is particularly well suited forutilization in dosimetric investigations, especially in conjunction withexposure to different physical and chemical agents in the workingenvironment, where a simple, easily handled, miniaturised recordingapparatus, which can be worn by a person is of great worth, as well asthe possibility of rapid and simple reading of measurement valuesobtained. The invention is, however, generally usuable in conjunctionwith data registration, where a time function of a measured quantity isrequired, e.g. in industrial process monitoring, long-term registrationof climatic variables, recording speed-ometers, etc, above all wheregraphical display in a bar chart diagram is of interest.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of an exemplifyingembodiment, while referring to the appended drawings containing fourfigures.

FIG. 1 very schematically illustrates the construction of an apparatusin accordance with the invention, the electrical part thereof being inblock diagram form, while the main features of the emission generationand registration part are shown in perspective.

FIG. 2 schematically illustrates the construction of a level ormeasuring interval separator included in the block diagram of FIG. 1, aswell as the emission generation and registration part, seen from above.

FIG. 3 is a schematic sectional view of an example of how the emissiongeneration and registration components of the apparatus may be arrangedin a casing.

FIG. 4 illustrates in a schematic perspective view the arrangement ofFIG. 3 with a film magazine part included therein in a swung-outposition.

DETAILED DESCRIPTION OF EMBODIMENT

The apparatus illustrated in FIGS. 1 and 2 is arranged for 4-channelregistration in the form of a bar chart, which thus comprises fourseparately readable bar registrations. Three of the channels and theircorresponding bars are intended for registering a measured quantitywithin three mutually separated measuring intervals, while the fourthchannel is intended for pure time registration, i.e. registration of thetotal time for the registration sequence.

The apparatus includes a measurement signal transducer 1, fortransmitting a measurement signal, the magnitude of which is dependenton the value of the measured quantity, to an amplifier 2. The amplifiedsignal leaving the amplifier is applied to a level or measuring intervalseparator 3. Depending on whether the applied signal is greater than afirst set value, but less than a second set value or lies between thesecond and a third set value or is greater than the third set value,said separator 3 emits a control signal respectively on a first outputline 4, a second output line 5 or a third output line 6. Each of lines4,5 and 6 are connected to an associated respective driving stage 7,8and 9 for respective LEDs 10,11 and 12. A fourth LED 13 is arranged tobe driven by an associated driving stage 14.

Each of the units 1,2,3,7,8 and 9 are supplied with current via a line15 when a power supply circuit 16 energising the apparatus is closed.The driving stage 14 is also supplied with current via line 15, but isfurther arranged to supply driving power to its associated LED 13 assoon as there is power on line 15. The driving stages 7,8 and 9,however, are arranged to give driving power to their respective LEDsonly when they also receive a control signal on the respective line4,5,6.

It will thus be understood that when the apparatus is energised, LED 13emits radiation continuously, while only one of LEDS 10,11,12 emitsradiation at a time, in response to the magnitude of the signal obtainedfrom the measurement signal transducer 1.

Each of LEDs 10-13 is adapted for generating and emitting radiationhaving constant intensity. The emission or radiation flow 20,21,22 and23, respectively, from the respective LED (only one of flows 20-22 ispresent at a time) is separated from the other radiation flows with theaid of suitable means 24-27, indicated in FIG. 2, but not more closelyshown, and said flow is directed to an allotted zone of a film 28, ofconstant sensitivity to radiation, via a respective filter 30,31,32,33and a respective aperture slit 34,35,36,37 in an aperture means 38arranged between the film 28 and the LEDs. Each filter has a specialattenuating characterisic, attenuating ability of the filter increasingvertically from bottom to top. A stepwise increase is assumed in thepresent case (the filter may be assumed to have five partial sectionswith constant attenuating ability in each section), although there couldbe a continuously logarithmically increasing attenuating ability, forexample. Each LED will thus irradiate a bar-shaped zone on the film, thedose of irradiation received per time unit will be different for thefive film zone portions or parts corresponding to the five partialsections of the associated filter, and it will be stepwise decreasingfrom the bottom and upwards.

The filters 30-33 preferably are "grey wedges" consisting of suitablyshaded or darkened film (having stepwise increasing shading or darkeningin the example). The filters will thereby be simple to manufacture andto arrange, while at the same time there is ensured very goodreproduceability of the attenuating characteristics. Furthermore, itwill be very simple to change filters in conjunction with a change inregistration task.

The film 28 is suitably of the monochrome, fine-grain, high-constrasttype, with low constant light sensitivity, so-called document film.

It will thus be understood that the height of the directly readabledarkening or shading in the respective bar on the film, after aregistration sequence (and subsequent developing), will be dependent onthe time during which the LED of the associated channel or measuringinterval has been energised so as to emit radiation, or in other wordson the integrated measured quantity value of the measuring interval inquestion. Since the selected attenuation characteristic and film sensityof the filter are known, and with knowledge of previously producedcalibration values, the readable bar height will be directly readablemeasure of the desired measurement value of the associated measuringinterval. In respect of the time channel, the readable bar heightobtained will naturally be, in a similar way, a directly readablemeasure of the total registration time, i.e. the time the apparatus hasbeen energised. In conjunction with the use of miniature format film,reading off the height of the respective bar is suitably done with theaid of graduated measurement magnifier.

An example of how the level separator 3 may be made, will soon bedescribed while referring to FIG. 2. The separator 3 shown in thisfigure includes three threshold circuits 40,41,42, the inputs of whichare connected to the output of amplifier 2 via associated, adjustablesignal attenuating elements 43,44, and 45, respectively, shown here assimple potentiometers. The output of threshold circuit 40 is connectedto driving stage 7 via a blocking circuit 46. Similarly thresholdcircuit 41 is connected to driving stage 8 via a blocking circuit 47.The output of threshold circuit 42 is connected directly to drivingstage 9. The control input of blocking circuit 46 is connected to theoutput of threshold circuit 41. The control input of blocking circuit 47is connected to the output of threshold circuit 42. The blockingcircuits' function is to block signal passage when there is a signal onthe respective control input.

The threshold circuits' function is to emit a driving amplifier controlsignal from the respective output as long as the input signal on therespective input exceeds a given level. With suitable adjustment ofelements 43-45, accordingly circuit 40 emits a signal when the signalsupplied from amplifier 2 exceeds the above-mentioned first set value,circuit 41 emits a signal when the supplied signal exceeds the secondset value, and circuit 42 emits a signal when the supplied signalexceeds the third set value. Blocking circuits 46,47 ensure that onlythe driving stage control signal, corresponding to the highest thresholdfunction, is allowed to pass on to the associated driving stage. FIGS. 3and 4 illustrate very schematically how the inventive apparatus may bearranged in a casing. This consists of two parts, namely a housing part50, open on one side, and accommodating all the electric components andnecessary filters, and a lid and film magazine part 51 closing off thehousing part and containing the slit aperture 38 and film 28. This part51 can be swung out and is removable. In the illustrated embodiment, thefour filters 30-33 are combined into a single filter 52 having a widthsuch that each of its transversely extending partial sections 53 coverall four parallel radiation channels. Filter 52 is arranged in theopening of housing part 50 for easy interchangeability and has anoutwardly curved configuration. Aperture 38 is arranged in the openingof lid part 51 and is inwardly curved for matching with filter 52 in theclosed position illustrated in FIG. 3. The film 28 is arranged behindaperture 38, the plane of the film having corresponding curvature. LEDs10-13 are arranged in housing part 50, and centrally in relation to thecurved film plane, so that the distance between film and diode issubstantially the same for the entire film plane.

Although the invention has been described in more detail above by meansof an example, in which a grey shading filter has been utilized toprovide selective attenuation of the radiation, it is emphasized thatthe use of other filtering techniques is possible. Thus, registration onthe film could be controlled using colour film technique (preferablyortho- or panchromatic) with filter functions provided by complementarycolours giving different continuous or stepwise extinction curves. Theemission or radiation signal which darkens or shades the film could alsobe regulated using a polarizing technique. Stepwise transmissivitydifferences may thus be provided in a filter containing polarizingfilter portions having stepwise differing optical axis. In this case,the registration threshold (the sensitivity adapted to different inputvalues/time duration fro the measurement) can also be variedmechanically by a rotatable polarizing filter in front of the LED.

If it is desired to have the registration result in clear showing, atransparent scale, possibly with numerical values, may be placed in thegap between filter and film. After the registration the scale thenappears with its highest value corresponding to the highest shaded partof the filter and the result can be seen in a clear manner. A fixedscale may alternatively be pre-exposed on the film to one side of thebars.

A still further simplification may be obtained in the cases where it ispossible to use a film of the Polaroid® type, since the specialdevelopment requirement would no longer be applicable. If such film of alarger format is used, after a registration sequence the measurementvalues of registrations obtained may be read off almost immediately,directly with the aid of a simple graduated ruler.

Further changes and modifications are, of course, possible within thescope of the invention, such as are defined by the following claims.

We claim:
 1. A method of registering a time-dependent quantity to bemeasured, present in the form of an electric signal, said signal beingtransformed, in response to a preselected measured quantity valueinterval, into an emission flow, said emission acting on a recordingelement arranged to detect and to register said emission such that theelement is thereby provided with a subsequently readable, integratedmeasurement value registration corresponding to a time function of themeasured quantity, characterized in that the emission flow acts onseveral parts of said element with a spread-out distribution in theshape of a bar comprising said parts, such that each part is given areadable partial registration, when the part in question has beensubjected to an emission effect providing a registering effect per timeunit, which for the various parts of the zone of said element affectedby emission has a predetermined magnitude unique to the respective part,wherewith, subsequent to registration process, each part having areadable partial registration indicates that there has been registeredat least one integrated measurement value corresponding to said part,whereby the greatest partial measurement value represents a directlyreadable, integrated measurement value.
 2. A method as claimed in claim1, characterized by causing the emission intensities incident on thevarious parts of the zone of said element affected by said emission tobe reduced in relation to each other.
 3. A method as claimed in claim 2,characterized in that by selective filtering of the emission flow thelatter is caused to be incident with different intensitites onrespective parts of the zone of said element acted on by the emission.4. The method of claim 2 wherein said reduction is provided by anelement having different emission sensitivities corresponding to thevarious parts of the zone affected by emission.
 5. A method as claimedin any one of the preceding claims, characterized by giving the variousparts of said element different pre-registrations, so that inconjunction with a registration sequence, each part is given a readablepartial registration for a particular emission effect, unique to thepart in question.
 6. Apparatus for registering a time-dependent quantityto be measured, present in the form of an electric signal, saidapparatus comprising conversion means for converting the electric signalto an emission flow which is specifically allotted a measurement valueregistration, including means for controlling the conversion in responseto the measured quantity value so that conversion and registration inconjunction therewith take place when the measured quantity value iswithin a predetermined interval; an element for detecting andintergratingly registering the emission in question; and emissioncontrol means for causing the emission flow generated by said conversionmeans to be incident on said detecting and registering element foraffecting said element, such that it is given an integrated measurementvalue registration corresponding to a time function of the measuredquantity value, the apparatus being characterized in that saidconversion and emission control means provide the incidence of saidemission flow on a zone of said element, said zone consisting of anumber of parts in the form of a bar; and filter means arrangedselectively to dampen the emission flow portions associated with therespective parts of the zone acted on by the emission for causing theemission flow to be incident with different intensities on respectiveparts of the emission-affected zone of said element for giving areadable partial registration for the part in question.
 7. Apparatus asclaimed in claim 6, characterized in that the various parts of the zoneaffected by the emission have different emission sensitivities. 8.Apparatus as claimed in claim 6 or 7, characterized in that the variousparts of the zone affected by emission have different preregistrations.